This invention concerns a drill bit direct drive for deep well drilling tools.
With a known drill bit direct drive of this type (German Patent No. 3,513,124), the bearing segments are each arranged at the free end of a bending bar that is a shaped component of the bearing ring. Such an axial bearing design is especially low in wear, because it permits formation of a gap that converges relative to the bearing segments in the direction of rotation of the bearing ring and the oil well fluid can form a lubricant film in this gap. The bending bars are also suitable for absorbing very high loads, but they have a very small spring range in operation and therefore impart only a very small equalization of tolerance to the axial bearing per trace ring/bearing ring pair. In cases when a relatively great equalization of tolerance by the axial bearing is necessary, the axial bearing must have a number of trace ring/bearing ring pairs which is in turn associated with high costs and also a substantial structure size of the axial bearing.
This invention is based on the problem of creating a drill bit direct drive with an axial bearing that is suitable especially for low axial loads, is inexpensive and yields a greater equalization of tolerance per trace ring/bearing ring pair.
The tiltability achieved with the axial bearing of the drill bit direct drive according to his invention makes it possible to form a lubricant gap in operation and thus permits operation under favorable wear conditions. The spring assembly supporting the bearing body permits axial shifting of the bearing body with a far greater spring range, so the bearing yields a great equalization of tolerance. The disk springs made of special spring steel are especially insensitive to temperatures, they resist wear despite the abrasive effect of the drilling fluid and they present especially favorable static and dynamic friction values. The load bearing capacity of a trace ring/bearing ring pair is lower in comparison with the known bearing with bending bar support of the bearing segment but can be adapted more easily to the given load requirements, because the spring characteristics can be varied more easily and inexpensively by changing the spring assembly than those of a bending bar shaped in the bearing ring .